Case Study: Lawa’i Solar (Hawaii) 28 MW DC PV + 100 MWh, 5-hour Battery Energy Storage System

In late 2016, the Kauai Island Utility Cooperative (KIUC) awarded a Power Purchase Agreement (PPA) and Interconnection Agreement to AES after a competitive bid process in which KIUC sought proposals for a solar PV + energy storage solution on the island of Kauai. AES and KIUC signed a PPA on December 30, 2016 for a 20 MW AC power plant comprised of 28 MW DC of integrated solar PV and 100 MWh battery energy storage system (BESS) located in Lawa’i, Kauai. The plant will provide a dispatchable renewable power capacity resource (electricity that can be dispatched at the request of the power grid operators) through a combination of direct PV generation, simultaneous PV and battery output, and battery discharge. Energy from the solar is stored in the BESS or delivered directly to the grid. KIUC will use the stored energy to reduce their evening peaks and provide consistent night-time power. A statistical dispatch model has been developed internally to meet reactive power obligations and to take a conservative stance on efficiency. The system will provide 11% of the island’s power and offset an estimated 53,000 MWh in the first year of operation.